This invention relates to a down-the-hole drill tool, said drill tool being adapted to drill a hole in advance of a trailing casing tube, said drill tool including a central pilot bit, a reamer means and a guide means for guiding said drill tool and said casing tube relative to one another, and a shaft that is adapted to be connected to a down-the-hole hammer. The invention also relates to a guide means and a one-piece unit being parts of the drill tool according to the present invention.
In known drill tools of the above-mentioned type the thread connection, e.g. between the guide means and the portion supporting the reamer, is the weak point Therefore it is an aim of the present invention to present a structural design of a drill tool of the type in question that avoids thread connections in portions of the drill tool that is subjected to high bending forces Also there is always a loss of energy in thread connections transferring impact energy.